System and method for facilitating hybrid message matching in a network interface controller (nic)

ABSTRACT

A network interface controller (NIC) capable of hybrid message matching is provided. The NIC can be equipped with a host interface, a hardware endpoint, and an endpoint management logic block. The host interface can couple the NIC to a host device. The hardware endpoint can facilitate a point of communication for an application running on the host device. The endpoint management logic block can maintain a list for storing a message associated with an endpoint represented by the hardware endpoint. The endpoint management logic block can then determine whether the utilization of the list is higher than a threshold. If the utilization is higher than the threshold, the endpoint management logic block can set a state of the endpoint to indicate that the endpoint is software managed. The NIC thus can transfer the control of the endpoint from the hardware endpoint to a software process of the host device.

BACKGROUND Field

This is generally related to the technical field of networking. More specifically, this disclosure is related to systems and methods for facilitating hybrid message matching in a network interface controller (NIC).

Related Art

As network-enabled devices and applications become progressively more ubiquitous, various types of traffic as well as the ever-increasing network load continue to demand more performance from the underlying network architecture. For example, applications such as high-performance computing (HPC), media streaming, and Internet of Things (JOT) can generate different types of traffic with distinctive characteristics. As a result, in addition to conventional network performance metrics such as bandwidth and delay, network architects continue to face challenges such as scalability, versatility, and efficiency.

SUMMARY

A network interface controller (NIC) capable of hybrid message matching is provided. The NIC can be equipped with a host interface, a hardware endpoint, and an endpoint management logic block. The host interface can couple the NIC to a host device. The hardware endpoint can facilitate a point of communication for an application running on the host device. The endpoint management logic block can maintain a list for storing a message associated with an endpoint represented by the hardware endpoint. The endpoint management logic block can then determine whether the utilization of the list is higher than a threshold. If the utilization of the list is higher than the threshold, the endpoint management logic block can set a state of the endpoint to indicate that the endpoint is software managed. In this way, the NIC can transfer the control of the endpoint from the hardware endpoint to a software process of the host device.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows an exemplary network.

FIG. 2A shows an exemplary NIC chip with a plurality of NICs.

FIG. 2B shows an exemplary architecture of a NIC.

FIG. 3A shows an exemplary NIC that can facilitate hybrid message matching.

FIG. 3B shows an exemplary hybrid message matching process in a NIC.

FIG. 4A shows a flow chart of a control transfer process for hybrid message matching in a NIC.

FIG. 4B shows a flow chart of a hybrid message matching process in a NIC.

FIG. 4C shows a flow chart of a hybrid message matching process in a host device.

FIG. 5 shows an exemplary computer system equipped with a NIC that facilitates message matching process.

In the figures, like reference numerals refer to the same figure elements.

DETAILED DESCRIPTION

Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present disclosure. Thus, the present invention is not limited to the embodiments shown.

Overview

The present disclosure describes systems and methods that facilitate hybrid message matching in a network interface controller (NIC). The NIC allows a host to communicate with a data-driven network. The network can accommodate dynamic data traffic with fast, effective congestion control by maintaining state information of individual packet streams. More specifically, packets injected into the network of switches can be categorized into streams, which can be mapped to their layer-2, layer-3, or other protocol-specific header information. Each stream can be marked by a distinctive identifier that is local to an input port of a switch, and provided with a stream-specific input buffer so that each stream can be individually flow-controlled. In addition, packets of a respective stream can be acknowledged upon reaching the egress point of the network, and the acknowledgment packets can be sent back to the ingress point of the stream along the same data path in the reverse direction. As a result, each switch can obtain state information of active packet streams it is forwarding and can perform highly responsive, stream-specific flow control. Such flow control can allow the network to operate at higher capacity while providing versatile traffic-engineering capabilities.

The embodiments described herein solve the problem of managing resources of a NIC for message matching by (i) determining whether the sources allocated for message matching in a NIC have reached near exhaustion, and (ii) transferring message matching operations to the host device. The NIC can transfer the message matching operations back to NIC from the host device when resources become available.

The NIC can be equipped with a list-processing engine (LPE) that can perform atomic search and search-with-delete operators in the various lists defined by the message passing interface (MPI) protocol and can dispatch list operations to correct matching units. To enhance speed, multiple processing elements can be used, and each processing element can include multiple memory banks, which are interconnected using a crossbar. In addition, the LPE achieves list-matching acceleration by separation of endpoints. An endpoint can be a point of communication between the NIC and the host device for an application programming interface (API) (e.g., MPI). The endpoint can facilitate access to the resources of the NIC for performing operations.

The LPE can maintain a set of physical endpoints. The LPE can facilitate the hardware endpoints to support typical use cases. However, the number of physical endpoints can be significantly less than the logical endpoints needed for a respective application using the API. The NIC may have finite resources that have to be shared between the endpoints. The resources can include buffers to store messages that have not been matched to requests and list entries to store requests that have not been matched to messages. If an application generates more messages than the NIC can store, the resources may become occupied. Typically, the NIC may impose flow control on such messages. The use of such a mechanism can adversely affect the performance.

To solve this problem, the NIC can transfer the control of message matching associated with an endpoint to the host processor upon detecting that the resources are near exhaustion. The NIC can transfer the control back to the NIC when resources become available. In some embodiments, the NIC can maintain respective thresholds for buffers and list entries that may store messages and requests, respectively. If the utilization of a resource reaches the corresponding threshold, the NIC may set the state of an endpoint as “software managed,” thereby transferring the control of the endpoint to the processor of the host device. The application (e.g., the provider layer implementation of MPI) may select a set of hardware endpoints in the NIC and a set of software endpoints managed by the processor.

During operation, the LPE may detect a message associated with an endpoint. If the endpoint is in the software-managed state, the LPE may attempt to allocate capacity in a request list for the message and in an event queue for a corresponding event. If the LPE succeeds with the allocations, the LPE may insert a respective request associated with the message to the buffers provided by the request list. The buffer can be referred to as a request buffer. Upon writing the entire message in the request buffer, the LPE can generate an event notifying the processor that a new request buffer is available for processing. On the other hand, if either of the allocations fails, the LPE may assert flow control on the endpoint.

The processor (e.g., a software process function running on the processor) can then obtain the message from the request buffer and match the message them against the priority list maintained in the memory of the host device. If the processor does not find a match based on the search, the processor can append the header information of the message into an unexpected list maintained in the memory of the host device. The processor may leave the payload data (e.g., the requests) in the request buffer. As the application continues to make MPI calls, the network stack of the host device may generate a receive request and attempt to match the received request against the header in the unexpected list. If the processor does not find a match based on the search, the processor can append the received request to the priority list. If either search succeeds, the processor can determine that the match is complete.

One embodiment of the present invention provides a NIC that can be equipped with a host interface, a hardware endpoint, and an endpoint management logic block. The host interface can couple the NIC to a host device. The hardware endpoint can facilitate a point of communication for an application running on the host device. The endpoint management logic block can maintain a list for storing a message associated with an endpoint represented by the hardware endpoint. The endpoint management logic block can then determine whether the utilization of the list is higher than a threshold. If the utilization of the list is higher than the threshold, the endpoint management logic block can set a state of the endpoint to indicate that the endpoint is software managed. In this way, the NIC can transfer the control of the endpoint from the hardware endpoint to a software process of the host device.

In a variation on this embodiment, the endpoint management logic block can determine that a message in an input buffer of the network interface controller is associated with the endpoint. The endpoint management logic block can then determine, based on the state, that the endpoint is a software endpoint.

In a further variation, the endpoint management logic block can determine whether the message matches a priority list of the NIC. If the message matches the priority list, the endpoint management logic block can process the message at the NIC.

In a further variation, the endpoint management logic block can allocate capacity in a request buffer for the message and in an event queue for an event. The event queue can be in the memory of the host device.

In a further variation, the endpoint management logic block can insert a respective request of the message into the allocated capacity of the request buffer.

In a further variation, the endpoint management logic block can generate an event for the host device and insert the event into the event queue. In this way, the NIC can notify the software process of the host device regarding the presence of the request buffer.

In a further variation, the endpoint management logic block can assert flow control for the endpoint in response to the unsuccessful allocation of the capacity.

In a variation on this embodiment, the endpoint management logic block can provide message headers to the software process for generating an unexpected list in a memory of the host device.

In a variation on this embodiment, if the utilization of the list is higher than the threshold, the address logic block can reject incoming append requests associated with the endpoint.

In a variation on this embodiment, the list can be defined by a message passing interface (MPI) protocol.

In this disclosure, the description in conjunction with FIG. 1 is associated with the network architecture and the description in conjunction with FIG. 2A and onward provide more details on the architecture and operations associated with a NIC that supports efficient management of idempotent operations.

FIG. 1 shows an exemplary network. In this example, a network 100 of switches, which can also be referred to as a “switch fabric,” can include switches 102, 104, 106, 108, and 110. Each switch can have a unique address or ID within switch fabric 100. Various types of devices and networks can be coupled to a switch fabric. For example, a storage array 112 can be coupled to switch fabric 100 via switch 110; an InfiniBand (IB) based HPC network 114 can be coupled to switch fabric 100 via switch 108; a number of end hosts, such as host 116, can be coupled to switch fabric 100 via switch 104; and an IP/Ethernet network 118 can be coupled to switch fabric 100 via switch 102. In general, a switch can have edge ports and fabric ports. An edge port can couple to a device that is external to the fabric. A fabric port can couple to another switch within the fabric via a fabric link. Typically, traffic can be injected into switch fabric 100 via an ingress port of an edge switch, and leave switch fabric 100 via an egress port of another (or the same) edge switch. An ingress link can couple a NIC of an edge device (for example, an HPC end host) to an ingress edge port of an edge switch. Switch fabric 100 can then transport the traffic to an egress edge switch, which in turn can deliver the traffic to a destination edge device via another NIC.

Exemplary NIC Architecture

FIG. 2A shows an exemplary NIC chip with a plurality of NICs. With reference to the example in FIG. 1, a NIC chip 200 can be a custom application-specific integrated circuit (ASIC) designed for host 116 to work with switch fabric 100. In this example, chip 200 can provide two independent NICs 202 and 204. A respective NIC of chip 200 can be equipped with a host interface (HI) (e.g., an interface for connecting to the host processor) and one High-speed Network Interface (HNI) for communicating with a link coupled to switch fabric 100 of FIG. 1. For example, NIC 202 can include an HI 210 and an HNI 220, and NIC 204 can include an HI 211 and an HNI 221.

In some embodiments, HI 210 can be a peripheral component interconnect (PCI) or a peripheral component interconnect express (PCIe) interface. HI 210 can be coupled to a host via a host connection 201, which can include N (e.g., N can be 16 in some chips) PCIe Gen 4 lanes capable of operating at signaling rates up to 25 Gbps per lane. HNI 210 can facilitate a high-speed network connection 203, which can communicate with a link in switch fabric 100 of FIG. 1. HNI 210 can operate at aggregate rates of either 100 Gbps or 200 Gbps using M (e.g., M can be 4 in some chips) full-duplex serial lanes. Each of the M lanes can operate at 25 Gbps or 50 Gbps based on non-return-to-zero (NRZ) modulation or pulse amplitude modulation 4 (PAM4), respectively. HNI 220 can support the Institute of Electrical and Electronics Engineers (IEEE) 802.3 Ethernet-based protocols as well as an enhanced frame format that provides support for higher rates of small messages.

NIC 202 can support one or more of: point-to-point message passing based on Message Passing Interface (MPI), remote memory access (RMA) operations, offloading and progression of bulk data collective operations, and Ethernet packet processing. When the host issues an MPI message, NIC 202 can match the corresponding message type. Furthermore, NIC 202 can implement both eager protocol and rendezvous protocol for MPI, thereby offloading the corresponding operations from the host.

Furthermore, the RMA operations supported by NIC 202 can include PUT, GET, and Atomic Memory Operations (AMO). NIC 202 can provide reliable transport. For example, if NIC 202 is a source NIC, NIC 202 can provide a retry mechanism for idempotent operations. Furthermore, connection-based error detection and retry mechanism can be used for ordered operations that may manipulate a target state. The hardware of NIC 202 can maintain the state necessary for the retry mechanism. In this way, NIC 202 can remove the burden from the host (e.g., the software). The policy that dictates the retry mechanism can be specified by the host via the driver software, thereby ensuring flexibility in NIC 202.

Furthermore, NIC 202 can facilitate triggered operations, a general-purpose mechanism for offloading, and progression of dependent sequences of operations, such as bulk data collectives. NIC 202 can support an application programming interface (API) (e.g., libfabric API) that facilitates fabric communication services provided by switch fabric 100 of FIG. 1 to applications running on host 116. NIC 202 can also support a low-level network programming interface, such as Portals API. In addition, NIC 202 can provide efficient Ethernet packet processing, which can include efficient transmission if NIC 202 is a sender, flow steering if NIC 202 is a target, and checksum computation. Moreover, NIC 202 can support virtualization (e.g., using containers or virtual machines).

FIG. 2B shows an exemplary architecture of a NIC. In NIC 202, the port macro of HNI 220 can facilitate low-level Ethernet operations, such as physical coding sublayer (PCS) and media access control (MAC). In addition, NIC 202 can provide support for link layer retry (LLR). Incoming packets can be parsed by parser 228 and stored in buffer 229. Buffer 229 can be a PFC Buffer provisioned to buffer a threshold amount (e.g., one microsecond) of delay bandwidth. HNI 220 can also include control transmission unit 224 and control reception unit 226 for managing outgoing and incoming packets, respectively.

NIC 202 can include a Command Queue (CQ) unit 230. CQ unit 230 can be responsible for fetching and issuing host side commands. CQ unit 230 can include command queues 232 and schedulers 234. Command queues 232 can include two independent sets of queues for initiator commands (PUT, GET, etc.) and target commands (Append, Search, etc.), respectively. Command queues 232 can be implemented as circular buffers maintained in the memory of NIC 202. Applications running on the host can write to command queues 232 directly. Schedulers 234 can include two separate schedulers for initiator commands and target commands, respectively. The initiator commands are sorted into flow queues 236 based on a hash function. One of flow queues 236 can be allocated to a unique flow. Furthermore, CQ unit 230 can further include a triggered operations module 238, which is responsible for queuing and dispatching triggered commands.

Outbound transfer engine (OXE) 240 can pull commands from flow queues 236 in order to process them for dispatch. OXE 240 can include an address translation request unit (ATRU) 244 that can send address translation requests to address translation unit (ATU) 212. ATU 212 can provide virtual to physical address translation on behalf of different engines, such as OXE 240, inbound transfer engine (IXE) 250, and event engine (EE) 216. ATU 212 can maintain a large translation cache 214. ATU 212 can either perform translation itself or may use host-based address translation services (ATS). OXE 240 can also include message chopping unit (MCU) 246, which can fragment a large message into packets of sizes corresponding to a maximum transmission unit (MTU). MCU 246 can include a plurality of MCU modules. When an MCU module becomes available, the MCU module can obtain the next command from an assigned flow queue. The received data can be written into data buffer 242. The MCU module can then send the packet header, the corresponding traffic class, and the packet size to traffic shaper 248. Shaper 248 can determine which requests presented by MCU 246 can proceed to the network.

Subsequently, the selected packet can be sent to packet and connection tracking (PCT) 270. PCT 270 can store the packet in a queue 274. PCT 270 can also maintain state information for outbound commands and update the state information as responses are returned. PCT 270 can also maintain packet state information (e.g., allowing responses to be matched to requests), message state information (e.g., tracking the progress of multi-packet messages), initiator completion state information, and retry state information (e.g., maintaining the information required to retry a command if a request or response is lost). If a response is not returned within a threshold time, the corresponding command can be stored in retry buffer 272. PCT 270 can facilitate connection management for initiator and target commands based on source tables 276 and target tables 278, respectively. For example, PCT 270 can update its source tables 276 to track the necessary state for reliable delivery of the packet and message completion notification. PCT 270 can forward outgoing packets to HNI 220, which stores the packets in outbound queue 222.

NIC 202 can also include an IXE 250, which provides packet processing if NIC 202 is a target or a destination. IXE 250 can obtain the incoming packets from HNI 220. Parser 256 can parse the incoming packets and pass the corresponding packet information to a List Processing Engine (LPE) 264 or a Message State Table (MST) 266 for matching. LPE 264 can match incoming messages to buffers. LPE 264 can determine the buffer and start address to be used by each message. LPE 264 can also manage a pool of list entries 262 used to represent buffers and unexpected messages. MST 266 can store matching results and the information required to generate target side completion events. MST 266 can be used by unrestricted operations, including multi-packet PUT commands, and single-packet and multi-packet GET commands.

Subsequently, parser 256 can store the packets in packet buffer 254. IXE 250 can obtain the results of the matching for conflict checking. DMA write and AMO module 252 can then issue updates to the memory generated by write and AMO operations. If a packet includes a command that generates target side memory read operations (e.g., a GET response), the packet can be passed to the OXE 240. NIC 202 can also include an EE 216, which can receive requests to generate event notifications from other modules or units in NIC 202. An event notification can specify that either a fill event or a counting event is generated. EE 216 can manage event queues, located within host processor memory, to which it writes full events. EE 216 can forward counting events to CQ unit 230.

Hybrid Message Matching in NIC

FIG. 3A shows an exemplary NIC that can facilitate hybrid message matching. In this example, host device 300 can include a NIC 320. Host device 300 can include a processor 302, a memory device 304 (e.g., the system memory), and an interface system 306. An HI 322 of NIC 320 may couple NIC 320 with device 300 and facilitate the communication between device 300 and NIC 320. For example, if HI 322 is a PCIe interface, interface system 306 can be a PCIe system that provides a slot for HI 322. NIC 320 can include an LPE 324 that can perform atomic search and search-with-delete operators in the various lists defined by the MPI protocol and can dispatch list operations to correct matching units.

To enhance the speed, multiple processing elements can be used, and each processing element can include multiple memory banks, which are interconnected using a crossbar. In addition, LPE 324 can achieve list-matching acceleration by separation of endpoints. An endpoint can be a point of communication for an API (e.g., for MPI) between NIC 320 and an application 308 running on device 300. The endpoint can facilitate access to the resources of NIC 320 for performing operations. LPE 324 can maintain a set of physical endpoints, such as endpoint 330. LPE 324 can facilitate the hardware endpoints to support typical use cases.

However, the number of physical endpoints can be significantly less than the logical endpoints needed for application 308. NIC 320 may have finite resources that have to be shared between the endpoints. The resources can include an input buffer 328, which can store messages that have not been matched to requests, and list entries of request list 326, which can store requests that have not been matched to messages. If application 308 generates more messages than LPE 324 can store, the resources may become occupied. Typically, LPE 324 may impose flow control on such messages. The use of such a mechanism can adversely affect the performance.

To solve this problem, LPE 324 can transfer the control of message matching associated with an endpoint to processor 302 (e.g., a software process function 370 running on processor 302) upon detecting that the resources are near exhaustion. LPE 324 can transfer the control back to NIC 320 when resources become available. In some embodiments, LPE 324 can maintain respective thresholds for request list 326 and input buffer 328, respectively. If the utilization of a resource reaches the corresponding threshold, LPE 324 may set the state of an endpoint as “software managed,” thereby transferring the control of the endpoint to processor 302. Memory device 304 can store an event queue 312 to facilitate the transfer. Event queue 312 can store an event that can notify processor 302 regarding the presence of new requests.

Even if the control of a particular endpoint is transferred to processor 302, NIC 320 can maintain the control of other endpoints. Transferring the control can include transferring the responsibility of progression to processor 302. It should be noted that application 308 may use both hardware and software endpoints. The provider layer implementation of MPI of application 308 may select a set of hardware endpoints in NIC 320 and a set of software endpoints managed by processor 302.

FIG. 3B shows an exemplary hybrid message matching process in a NIC. During operation, LPE 324 may detect a message 310 associated with an endpoint 350 in input buffer 328. If endpoint 350 is in the software-managed state, LPE 324 may match message 310 against a local priority list 380 and determine that there is no priority list matching is found for message 310. Accordingly, LPE 324 may attempt to allocate capacity in request list 326 for message 310 and in event queue 312 for a corresponding event. If LPE 324 succeeds with the allocations, request list 326 may provide buffer 314. LPE 324 can then insert a respective request, such as requests 352 and 354, associated with message 310 into request buffer 314. Upon writing message 310 in its entirety in request buffer 314, LPE 324 can generate an event 360 (e.g., a PUT event) in event queue 312 to notify processor 302 that a new request buffer 314 is available for processing. On the other hand, if either of the allocations fails, LPE 324 may assert flow control on endpoint 350.

Processor 302 can then obtain message 310 from request buffer 314 and match message 310 against a software priority list 362. If processor 302 does not find a match based on the search, processor 302 can append the header information of message 310 into a software unexpected list 364. Processor 302 may leave the payload data (e.g., requests 352 and 354) in request buffer 314. As application 308 continues to make MPI calls, the network stack of device 300 may generate a receive request and attempt to match the received request against the header in unexpected list 364. If processor 302 does not find a match based on the search, processor 302 can append the received request to priority list 362. If either search succeeds, processor 302 can determine that the match is complete.

To determine whether to transfer (or offload) the control of endpoint 350 to NIC 320, process function 370 can check a set of transfer criteria. The set of transfer criteria can include one or more of: whether request buffer 314 is empty, whether unexpected list 364 is empty, and whether the utilization of priority list 362 is lower than a threshold (e.g., empty or close to empty). In some embodiments, process function 370 may periodically evaluate the transfer criteria. If process function 370 determines that the transfer criteria have been met, process function 370 can initiate the transfer of control to LPE 324.

Process function 370 can then send a request to NIC 320 to enable a hardware endpoint for endpoint 350. The request can include a current value of the read pointer, which can be represented by an offset from a base pointer, for request buffer 314. A value of zero may indicate that request buffer 314 is empty. Upon receiving the request, LPE 324 can compare the pointer received in the request with a copy of the pointer maintained at LPE 324. If the two pointers match, the transfer can be successful. As a result, the subsequent messages can be directed to NIC 320 instead of request buffer 314. Furthermore, process function 370 can send append requests to LPE 324 for the entries in priority list 362 and any subsequent requests. Until the resources of NIC 320 reach near exhaustion again, LPE 324 can continue with the message matching in NIC 320. On the other hand, if the two pointers do not match, LPE 324 may have added a new message in request buffer 314. As a result, LPE 324 can send a failure notification to process function 370. Upon receiving the failure notification, process function 370 may re-evaluate the transfer criteria.

FIG. 4A shows a flow chart of a control transfer process for hybrid message matching in a NIC. During operation, an LPE of the NIC can receive an unexpected message or append a request associated with an endpoint (operation 402). The LPE can determine whether the resources of the NIC are near exhaustion (operation 404). If the resources of the NIC are not near exhaustion, the LPE can maintain the endpoint in the NIC (operation 416). On the other hand, if the resources of the NIC are near exhaustion, the LPE can set the endpoint state as “software managed” (operation 406) and signals the processor to control the endpoint (operation 408). The LPE can then reject incoming append requests at the NIC (operation 410) and provide message headers for generating an unexpected list in the memory (operation 412). The LPE can then handover the matching operations to the processor (operation 414).

FIG. 4B shows a flow chart of a hybrid message matching process in a NIC. During operation, an LPE of the NIC can receive a message and match against a priority list (operation 432). The LPE can then check whether the match has been successful (operation 434). If the match has been successful, the message can be associated with an older receive buffer, which could have been allocated before transferring control to the process function (e.g., process function 370 in FIG. 3B). Accordingly, the LPE can perform process the message at the NIC (operation 446). On the other hand, if the match has not been successful, the message can be one that should be matched by the process function.

Hence, the LPE can allocate capacity (e.g., a buffer) in a request list for a received message and in an event queue for an event (operation 436). The LPE can then check whether the allocations have been successful (operation 438). If the allocations have not been successful, the LPE can assert flow control on the endpoint associated with the message (operation 448). On the other hand, if the allocations have been successful, the LPE can insert a respective request in the message into the buffer of the request list (operation 440). The LPE can then generate an event and insert the event into the event queue (operation 442). Subsequently, the LPE can notify the process function regarding the presence of a new buffer (operation 444).

FIG. 4C shows a flow chart of a hybrid message matching process in a host device. During operation, a process function of the host device can obtain a message from the request buffer (operation 452) and match against the priority list (operation 454). The function can then check whether the match has been successful (operation 456). If the match has not been successful, the function can append the header information to the unexpected list (operation 458). The function can then generate a receive request based on the network stack of the device and match against the unexpected list (operation 460). If the match has been successful, the function can insert the received request in a priority list (operation 464) and check against the priority list (operation 454). On the other hand, if the match has been successful for the priority list (operation 456) or the unexpected list (operation 460), the function can determine the match to be complete (operation 466).

Exemplary Computer System

FIG. 5 shows an exemplary computer system equipped with a NIC that facilitates message matching process. Computer system 550 includes a processor 552, a memory device 554, and a storage device 556. Memory device 554 can include a volatile memory device (e.g., a dual in-line memory module (DIMM)). Furthermore, computer system 550 can be coupled to a keyboard 562, a pointing device 564, and a display device 566. Storage device 556 can store an operating system 570. An application 572 can operate on operating system 570.

Computer system 550 can be equipped with a host interface coupling a NIC 520 that facilitates efficient data request management. NIC 520 can provide one or more HNIs to computer system 550. NIC 520 can be coupled to a switch 502 via one of the HNIs. NIC 520 can include an endpoint management logic block 530 (e.g., in an LPE of NIC 520). Endpoint management logic block 530 can facilitate efficient message matching in NIC 520, and may include a resource logic block 532, a control logic block 534, and a matching logic block 536.

Control logic block 532 can determine whether the resources in NIC 520 has become close to exhaustion (e.g., based on respective thresholds). If the resources in NIC 520 are close to exhaustion, control logic block 532 can transfer the control of an endpoint to an endpoint manager 540 that runs on processor 552. Endpoint manager 540 can facilitate the operations and resources for software endpoints, as described in conjunction with FIG. 4C. Allocation logic block 534 can allocate capacity (e.g., a buffer) in a request list for a received message and in an event queue for an event. Insertion logic block 536 can insert a respective request in the message into the buffer of the request list. Insertion logic block 536 can also generate an event and insert the event into the event queue.

In summary, the present disclosure describes a NIC that facilitates hybrid message matching. The NIC can be equipped with a host interface, a hardware endpoint, and an endpoint management logic block. The host interface can couple the NIC to a host device. The hardware endpoint can facilitate a point of communication for an application running on the host device. The endpoint management logic block can maintain a list for storing a message associated with an endpoint represented by the hardware endpoint. The endpoint management logic block can then determine whether the utilization of the list is higher than a threshold. If the utilization of the list is higher than the threshold, the endpoint management logic block can set a state of the endpoint to indicate that the endpoint is software managed. In this way, the NIC can transfer the control of the endpoint from the hardware endpoint to a software process of the host device.

The methods and processes described above can be performed by hardware logic blocks, modules, logic blocks, or apparatus. The hardware logic blocks, modules, logic blocks, or apparatus can include, but are not limited to, application-specific integrated circuit (ASIC) chips, field-programmable gate arrays (FPGAs), dedicated or shared processors that execute a piece of code at a particular time, and other programmable-logic devices now known or later developed. When the hardware logic blocks, modules, or apparatus are activated, they perform the methods and processes included within them.

The methods and processes described herein can also be embodied as code or data, which can be stored in a storage device or computer-readable storage medium. When a processor reads and executes the stored code or data, the processor can perform these methods and processes.

The foregoing descriptions of embodiments of the present invention have been presented for purposes of illustration and description only. They are not intended to be exhaustive or to limit the present invention to the forms disclosed. Accordingly, many modifications and variations will be apparent to practitioners skilled in the art. Additionally, the above disclosure is not intended to limit the present invention. The scope of the present invention is defined by the appended claims. 

What is claimed is:
 1. A network interface controller (NIC), comprising: a host interface to couple a host device; a hardware endpoint to facilitate a point of communication for an application running on the host device; and an endpoint management logic block to: maintain a list for storing a message associated with an endpoint, wherein the endpoint is represented by the hardware endpoint; determine whether utilization of the list is higher than a threshold; and in response to determining that utilization of the list is higher than the threshold, set a state of the endpoint to indicate that the endpoint is software managed, thereby transferring control of the endpoint from the hardware endpoint to a software process of the host device.
 2. The network interface controller of claim 1, wherein the endpoint management logic block is further to: determine that a message in an input buffer of the network interface controller is associated with the endpoint; and determine, based on the state, that the endpoint is a software endpoint.
 3. The network interface controller of claim 2, wherein the endpoint management logic block is further to: determine whether the message matches a priority list of the network interface controller; and in response to determining that the message matches the priority list, process the message at the network interface controller.
 4. The network interface controller of claim 2, wherein the endpoint management logic block is further to: allocate capacity in a request buffer for the message; and allocate capacity in an event queue for an event, wherein the event queue is in a memory of the host device.
 5. The network interface controller of claim 3, wherein the endpoint management logic block is further to insert a respective request of the message into the allocated capacity of the request buffer.
 6. The network interface controller of claim 3, wherein the endpoint management logic block is further to: generate an event for the host device; and insert the event into the event queue, thereby notifying the software process of the host device regarding presence of the request buffer.
 7. The network interface controller of claim 3, wherein the endpoint management logic block is further to assert flow control for the endpoint in response to unsuccessful allocation of the capacity.
 8. The network interface controller of claim 1, wherein the endpoint management logic block is further to provide message headers to the software process for generating an unexpected list in a memory of the host device.
 9. The network interface controller of claim 1, wherein, in response to determining that utilization of the list is higher than the threshold, the address logic block is further to reject incoming append requests associated with the endpoint.
 10. The network interface controller of claim 1, wherein the list is defined by a message passing interface (MPI) protocol.
 11. A method, comprising: maintaining, in a network interface controller (NIC), a hardware endpoint to facilitate a point of communication for an application running on a host device, wherein a host interface of the NIC is coupled to the host device; maintaining a list for storing a message associated with an endpoint, wherein the endpoint is represented by the hardware endpoint; determining whether utilization of the list is higher than a threshold; and in response to determining that utilization of the list is higher than the threshold, setting a state of the endpoint to indicate that the endpoint is software managed, thereby transferring control of the endpoint from the hardware endpoint to a software process of the host device.
 12. The method of claim 11, further comprising: determining that a message in an input buffer of the NIC is associated with the endpoint; and determining, based on the state, that the endpoint is a software endpoint.
 13. The method of claim 12, further comprising: determining whether the message matches a priority list of the NIC; and in response to determining that the message matches the priority list, processing the message at the NIC.
 14. The method of claim 12, further comprising: allocating capacity in a request buffer for the message; and allocating capacity in an event queue for an event, wherein the event queue is in a memory of the host device.
 15. The method of claim 13, further comprising inserting a respective request of the message into the allocated capacity of the request buffer.
 16. The method of claim 13, further comprising: generating an event for the host device; and inserting the event into the event queue, thereby notifying the software process of the host device regarding presence of the request buffer.
 17. The method of claim 13, further comprising asserting flow control for the endpoint in response to unsuccessful allocation of the capacity.
 18. The method of claim 11, further comprising providing message headers to the software process for generating an unexpected list in a memory of the host device.
 19. The method of claim 11, further comprising, in response to determining that utilization of the list is higher than the threshold, rejecting incoming append requests associated with the endpoint.
 20. The method of claim 13, wherein the list is defined by a message passing interface (MPI) protocol. 